Internationalisation is the process of making an application cross-cultural. This mostly involves support for multiple languages.
i18n is short for the web internationalisation standard.
You keep the first and last letters, and replace everything in between with the count of the letters replaced.
- internationalization => i18n
Given the text "Continue" on a button.
To support multiple languages, you need some label for "Continue" that points to the translation in each language.
But some words that are the same in English, will be translated to different words in some other language, based on context.
Therefore, you need the context included in the key for this term.
Instead of key "continue", you want something like "form_login:step_1:primary_button" vs "generic:continue".
Take singular/plural translactions into account. This can affect an entire sentence.
Ex: There is 1 item in the cart.
Ex: There are 2 items in the cart.
Keep html/styling/etc out of your translation files.
Ex: Don't put "<p><i>Go to next step</i></p>" in a language file.